In recent years, almost all aircraft fuel tanks are so-called integral tanks such as those described in Patent Literature 1, wherein the airframe structure itself forms the tank container. In one example of an integral tank, the region enclosed by the front spar, the rear spar, and the upper and lower wing skins, which represent sections of the main wing, is used as a tank. In other words, these structures are used as a container for storing fuel.
On the other hand, materials that are lightweight, high-strength and provide good durability are in demand for the airframe materials such as the main wing of the aircraft, and in recent years, the use of resin materials that have been reinforced with fiber (composite materials) has become more widespread.
For example, carbon fiber reinforced plastics (CFRP) prepared by immobilizing carbon fibers within an epoxy resin or the like are widely used as these composite materials.